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Extensions

Garden annexes

Self-contained living space in the garden for family or guests. Designed, approved and built by SK Residential, with a fixed price in writing for the agreed specification.

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What is a garden annexe?

A garden annexe is a separate single-storey building in the grounds of a house with its own bedroom, bathroom and kitchenette, used by family members as part of the main household. Unlike a garden office, an annexe that people sleep in normally needs planning permission and full building regulations approval.

Rendered single-storey garden annexe with slate roof and French doors at the end of a garden

We design annexes as permanent buildings with proper foundations, insulation and services, and we prepare the planning case showing how the annexe will be used as part of the main home. Connections for water, drainage and power are planned from the start.

Typical time on site
14 to 24 weeks
Guide price
£2,400 to £3,900 per m²
Building regulations
Required

What is included?

  • Design and planning application
  • Foundations and drainage connections
  • Brick, block or timber-frame structure
  • Kitchenette and shower room
  • Heating, hot water and electrics
  • Accessible design options for older relatives

How much does a garden annexe cost?

A 35 m² one-bedroom annexe typically costs around £100,000 to £120,000 including VAT at a good specification.

Garden annexesGuide price incl. VAT
Standard specification£2,400 to £2,900 per m²
Good specification£2,900 to £3,400 per m²
High specification£3,400 to £3,900 per m²

Unit: per m² of floor area. Guide ranges only; your price is fixed in writing after the survey.

Use the guide price tool for a figure based on your size and specification, or see all guide prices.

Does a garden annexe need planning permission?

England

A self-contained annexe used for sleeping and living normally needs planning permission in England. Permitted development for outbuildings does not cover living accommodation. Councils usually attach a condition that the annexe stays part of the main house.

Wales

In Wales an annexe with sleeping accommodation needs planning permission, usually with a condition tying it to the main house.

Scotland

In Scotland an annexe needs planning permission and a building warrant before work starts.

Northern Ireland

In Northern Ireland an annexe needs planning permission and building control approval.

What about building regulations?

Full building regulations approval is needed, as for any new home: fire safety, insulation, drainage, ventilation and access.

What should I think about before starting?

  • The annexe normally has to remain part of the main household, not let as a separate home.
  • Drainage may need a pump if the garden falls away from the sewer.
  • A level threshold and wider doors make the annexe suitable for later life.
  • Council tax treatment depends on who lives there; check with your council.

How does the project run?

  1. Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
  2. Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
  3. Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
  4. Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

Questions about garden annexes

Do I need planning permission for a garden annexe?

Usually yes, because people will sleep in it. Outbuilding permitted development does not cover living accommodation.

How much does a garden annexe cost?

Around £2,400 to £3,900 per square metre including VAT, depending on finish and services.

Can I rent the annexe out?

Usually not without a separate planning permission, because councils normally require it to stay part of the main house.

How long does an annexe take to build?

About 14 to 24 weeks on site after approvals.

Can you make it wheelchair accessible?

Yes. Level access, wider doors and a level-access shower can be designed in from the start.

Related projects

Where do we build garden annexes?

We take on garden annexes across England, Wales, mainland Scotland and Northern Ireland. Choose your area:

Planning an extension, loft or new home?

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